WLP refers to semiconductor packages that are formed at the wafer level prior singulation and then singulated into their individual dies. As a result WLP packages can have a small foot print size—often as small as the fabricated die itself. WLP can be formed on the same wafer as an active die or active dies can be attached to a wafer substrate.
WLP can streamline the semiconductor manufacturing process by fully integrating wafer fabrication, packaging and even testing.
In order to accommodate the miniaturization resultant from WLP, smaller solder balls are used. Often the solder balls used to interface a package to a printed circuit board (PCB) in assembly are relied upon to offer thermal dissipation. However, WLP packages suffer from diminished thermal dissipation due to the reduction in size and pitch of the solder balls.